Heat sink

ABSTRACT

A heat sink includes a radiator fin for dissipating heat of an electronic device provided on a printed board; a plurality of radiator fins included in the heat sink is formed in an arbitrary diameter size; and the radiator fins are connected to each other by inserting a pair of fastening screws through a through hole provided on each of the radiator fins, and a tip end of the fastening screws is screwed and fastened to a screw hole of a base heat sink fixed on the upper surface of an electronic device.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of International Application No. PCT/JP2007/071948, filed on Nov. 12, 2007, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are directed to a heat sink.

BACKGROUND

Recently, along with advances in functions and speed up of electronic devices (communication devices, server storages, or the like), electronic parts mounted on a printed board, such as a Large Scale Integration (LSI), or a Field Programmable Gate Array (FPGA), also have a tendency to speed up, to consume more electricity, and to generate more heat. It is also important to intend miniaturization of an electronic device including a printed board mounted with such electronic parts, in terms of cost reduction.

Conventionally, a heat sink configured to dissipate and to cool heat generated from electronic parts mounted on such printed board has been known (see Japanese Laid-open Patent Publication No. 54-008469). As such heat sink, a heat sink that includes a plurality of radiator fins in a disk shape is generally used, and such conventional heat sink is configured as an integral heat sink that is customized and designed in a dedicated manner by considering the size (physical shape) of a printed board and an electronic device A onto which the heat sink is to be mounted, and a cooling performance.

Configuration of Conventional Heat Sink

An overview of a conventional heat sink is explained below with reference to FIGS. 17A and 17B. FIG. 17A is a plan view of a conventional heat sink 1; and FIG. 17B is a side view of it.

As depicted in FIGS. 17A and 17B, the heat sink 1 is constructed by piling a plurality of pieces (three pieces in FIG. 17B) of radiator fins 3 in a thin disk shape in multiple layers around a column unit 2. The heat sink 1 configured in this way is fixed by fixing the underside of the column unit 2 of the heat sink 1 onto the upper side of the electronic device A (FIG. 19) mounted on a printed board, by using, such as an adhesive. The heat sink can cool the electronic device A by dissipating heat generated from the electronic device A with the radiator fins 3 included in the heat sink 1.

Although the conventional heat sink 1 described above can be mounted on a printed board in a low height, there is a problem that electronic parts, such as a damping resistance R and a bypass capacitor C, cannot be arranged around the electronic device A mounted on the printed board.

Problems about the conventional heat sink 1 described above are explained below with reference to FIGS. 18 to 22. FIG. 18 is a plan view that depicts a state that the conventional heat sink 1 is fixed on the upper surface of the electronic device A provided on a printed board P; and FIG. 19 is a side view of FIG. 18. The heat sink 1 that includes radiator fins having larger outside dimensions than the electronic device A is explained below as an example. A reference letter R in the figure denotes a damping resistance for reducing switching noise and electromagnetic noise of a signal; and a reference letter C denotes a bypass capacitor.

As depicted in FIGS. 18 and 19, when the heat sink 1 having larger outer dimensions (width) than those of the electronic device A is provided, there is no space in the vicinity of the heat sink 1 (the underside of the radiator fin 3 positioned at the lowest place in the structure of the heat sink 1) and around it (diagonally shaded areas in FIGS. 18 and 19), so that electronic parts (such as the damping resistance R and the bypass capacitor C) cannot be mounted. Consequently, there is a problem that because the electronic parts need to be arranged by keeping a distance from the electronic device A, high-density packaging cannot be achieved. Furthermore, there is a problem that because the damping resistance R and the bypass capacitor C for reducing electromagnetic noise cannot be arranged in the vicinity of the electronic device A as described above, an adverse effect is produced in electrical characteristics.

FIG. 20A depicts an example that the heat sink 1 is provided to each of the electronic devices A provided on the both sides of the front and the back of the printed board P. As depicted in the figure, when the electronic devices A are provided on the both sides of the front and the back of the printed board P, peripheral parts and electronic parts cannot be mounted on respective opposite sides; therefore, similarly to FIG. 19 described above, there is a problem that because the heat sink 1 is arranged on the upper surface of each of the electronic devices A, electronic parts cannot be arranged in the vicinity of the electronic device A (diagonally shaded areas in FIG. 20A). As a result, a problem occurs in terms of electrical characteristics, such as increase in power source noise or decrease in power source margin, because electronic parts, such as the damping resistance R and the bypass capacitor C cannot be mounted in the vicinity of the electronic devices A.

FIG. 20B depicts an example that the electronic devices A are mounted in a staggered manner on the both sides of the front and the back of the printed board P, and the heat sink 1 is provided on each of the electronic devices A. Similarly to FIG. 20A, also in this case, because the heat sink 1 is arranged on the upper surface of each of the electronic devices A, a problem occurs, such as increase in power source noise or decrease in power source margin, because electronic parts, such as the damping resistance R and the bypass capacitor C cannot be mounted in the vicinity of the electronic devices A (diagonally shaded areas in FIG. 20B). If an electronic part is arranged at a position distant from the electronic device A instead of the vicinity, a problem occurs that high-density packaging cannot be implemented because the packaging area is increased.

FIG. 21 depicts an example that there is an insert region (a part enclosed by broken lines in FIG. 21) of a plug that connects an optical module onto the underside of the printed board P, and the heat sink 1 is provided on the electronic device A provided on the upper surface of the printed board P. In this case, electronic parts, such as the damping resistance R and the bypass capacitor C, cannot be mounted in the insert region of the plug on the back side of the electronic device, and similarly to FIG. 20A, the heat sink 1 is arranged on the upper surface of the electronic device A; consequently, a problem occurs in terms of electrical characteristics, such as increase in power source noise or decrease in power source margin, because electronic parts, such as the damping resistance R and the bypass capacitor C, cannot be mounted in the vicinity of the electronic devices A (diagonally shaded area in FIG. 21).

FIG. 22A depicts an example that the electronic device A mounted on the printed board P on the main side faces to the back side of the printed board P′ on the sub side, and the heat sink 1 is provided on the electronic device A. Two circuit parts are mounted on the back side of the printed board P′ of the sub side. Precisely, as depicted in FIG. 22A, because a circuit part having a height is mounted on the back side of the printed board P′ of the sub side (on the right end of the printed board P′); in order to avoid contact between the circuit part and the radiator fin 3 of the heat sink 1, it is conceivable to arrange the circuit part by avoiding contact and keeping a distance from in the horizontal direction from the radiator fin 3; however, in such case, a problem arises in terms of packaging area such that high-density packaging in the horizontal direction is not implemented.

Moreover, as depicted in FIG. 22B, in order to avoid contact between the circuit part and the radiator fins 3 of the heat sink 1 by considering the height direction, a distance between the printed board P′ of the sub side and the printed board P of the main side needs to be extended to a certain distance (distance L). In such case, a problem arises in terms of packaging volume such that high-density packaging in the height direction is not implemented.

SUMMARY

According to an aspect of an embodiment of the invention, a heat sink includes radiator fins for dissipating heat of an electronic device provided on a printed board, wherein the heat sink is constructed by piling radiator fins formed in an arbitrary shape into multiple layers in a height direction and connecting the radiator fins.

The object and advantages of the embodiment will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the embodiment, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is an exploded view of an overall configuration of a heat sink according to a first embodiment of the present invention;

FIG. 1B is a side view of the heat sink according to the first embodiment;

FIG. 2A is a plan view of a radiator fin depicted in FIG. 1;

FIG. 2B is a side view of the radiator fin depicted in FIG. 1;

FIG. 3A is a plan view of a base heat sink depicted in FIG. 1;

FIG. 3B is a side view of the base heat sink depicted in FIG. 1;

FIG. 4A is an exploded view of an overall configuration of a heat sink according to a second embodiment of the present invention;

FIG. 4B is a side view of the heat sink according to the second embodiment;

FIG. 5A is a plan view of a radiator fin depicted in FIG. 4;

FIG. 5B is a side view of the radiator fin depicted in FIG. 4;

FIG. 5C is a partial view of the radiator fin depicted in FIG. 5B;

FIG. 6A is a plan view of a base heat sink depicted in FIG. 4;

FIG. 6B is a side view of the base heat sink depicted in FIG. 4;

FIG. 6C is a partial view of the base heat sink depicted in FIG. 6B;

FIG. 7A is an exploded view of an overall configuration of a heat sink according to a third embodiment of the present invention;

FIG. 7B is a side view of the heat sink according to the third embodiment;

FIG. 8A is a plan view of a radiator fin depicted in FIG. 7;

FIG. 8B is a side view of the radiator fin depicted in FIG. 7;

FIG. 8C is a partial view of the radiator fin depicted in FIG. 8B;

FIG. 9A is a plan view of a base heat sink depicted in FIG. 7;

FIG. 9B is a side view of the base heat sink depicted in FIG. 7;

FIG. 9C is a partial view of the base heat sink depicted in FIG. 9B;

FIG. 10A is an exploded view of an overall configuration of a heat sink according to a fourth embodiment of the present invention;

FIG. 10B is a side view of the heat sink according to the fourth embodiment;

FIG. 11A is a plan view of the first and the second radiator fins depicted in FIG. 10A;

FIG. 11B is a plan view of the third radiator fin depicted in FIG. 10A;

FIG. 12A is a plan view of a radiator fin depicted in FIG. 10B;

FIG. 12B is a side view of the radiator fin depicted in FIG. 10B;

FIG. 13 is a side view that depicts an application example of a heat sink;

FIG. 14 is a side view that depicts an application example of a heat sink;

FIG. 15 is a side view that depicts an application example of a heat sink;

FIG. 16 is a side view that depicts an application example of a heat sink;

FIG. 17A is a plan view of a radiator fin included in a conventional heat sink;

FIG. 17B is a side view that depicts an overall configuration of the conventional heat sink;

FIG. 18 is a plan view that depicts the conventional heat sink;

FIG. 19 is a side view that depicts the conventional heat sink;

FIG. 20A is a side view that depicts an application example of the conventional heat sink;

FIG. 20B is a side view that depicts an application example of the conventional heat sink;

FIG. 21 is a side view that depicts an application example of the conventional heat sink;

FIG. 22A is a side view that depicts an application example of the conventional heat sink; and

FIG. 22B is a side view that depicts an application example of the conventional heat sink.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention will be explained with reference to accompanying drawings. A first embodiment of the present invention depicts an application example of a heat sink to be mounted on an electronic device A provided on a printed board. The present invention is not limited by the first embodiment described below.

[a] First Embodiment Configuration of Heat Sink

A heat sink 10 according to the first embodiment is explained below in detail with reference to FIGS. 1A, 1B, 2A, 2B, 3A, and 3B. FIG. 1A is an exploded view of an overall configuration of the heat sink 10 according to the first embodiment and FIG. 1B is a side view of the heat sink 10. FIGS. 2A and 2B are a plan view and a side view of a radiator fin 11 depicted in FIG. 1, respectively. FIGS. 3A and 3B are a plan view and a side view of a base heat sink 15 depicted in FIG. 1A, respectively. The following description explains the heat sink 10 that is fixed on the upper surface of the electronic device A mounted on a printed board P. A reference letter R in the figure denotes a damping resistance for reducing switching noise and electromagnetic noise of a signal; and a reference letter C denotes a bypass capacitor.

A feature of the heat sink 10 according to the first embodiment is that a heat sink is constructed in a desired shape by dividing radiator fins of an integral type of a heat sink that is conventionally used and includes a plurality of radiator fins, and combining a plurality of radiator fins formed in an arbitrary size.

In other words, as depicted in FIG. 1A, the heat sink 10 includes a plurality of pieces of the radiator fins 11 formed in a plurality of thin disks (three pieces in FIG. 1), and the base heat sink 15 that fixes the radiator fins 11 on the upper surface of the electronic device A as the radiator fins 11 are piled in multiple layers in the height direction (vertical direction in FIG. 1A); and the radiator fins 11 are connected to each other with a pair of fastening screws 17. The sizes of the radiator fins 11 are formed in arbitrary diameters.

As depicted in FIGS. 2A and 2B, a fixed base 13 in a small disk shape is fixedly provided in the substantial center on the underside of the radiator fin 11, and a pair of through holes 14 that allows two of the fastening screws 17 to be inserted therethrough is formed on the fixed base 13. Moreover, in the substantial center on the upper side of the radiator fin 11, fitting holes 12 into which heads 18 of two of the fastening screws 17 can fit are formed.

On the other hand, as depicted in FIGS. 3A and 3B, a pair of screw holes 16 is formed on the base heat sink 15, and the screw holes 16 are configured to fasten the fastening screws 17 onto the base heat sink 15 under a state that the radiator fins 11 are connected by screwing in a screw part formed at a tip end of the fastening screw 17 inserted from the through hole 14 of the radiator fin 11.

A configuration example of the heat sink 10 that uses the radiator fins 11, the base heat sink 15, and the fastening screws 17 is explained below with reference to FIG. 1. In other words, as depicted in FIG. 1, two of the fastening screws 17 are each inserted through the through holes 14 formed on the fixed base 13 of three pieces of the radiator fins 11, and screw parts formed at the tip ends of the two of the fastening screws 17 are screwed and fastened into the pair of the screw holes 16 of the base heat sink 15. Accordingly, (the three pieces of) the radiator fins 11 can be constructed in a multilayered state as the heat sink 10. The heat sink 10 that the radiator fins 11 are piled in multiple layers can be mounted on the electronic device A by finally fixing the underside of the base heat sink 15 onto the upper surface of the electronic device A by using an adhesive.

As described above, according to the first embodiment, the heat sink 10 can be constructed as a plurality of the radiator fins 11 are formed in an arbitrary diameter, and the radiator fins 11 are connected to each other by inserting a pair of the fastening screws 17 through the through holes 14 provided on each of the radiator fins 11, and screwing in tip ends of the fastening screws 17 to the screw holes 16 of the base heat sink 15 fixed on the upper surface of the electronic device A; therefore a heat sink that has heat dissipation characteristics (cooling function) can be easily constructed by combining a plurality of radiator fins formed in an arbitrary shape, and the heat sink that is planned to achieve good electrical characteristics and designed at low cost without spending time and effort for a customized design can be constructed.

[b] Second Embodiment

A configuration of a heat sink 20 according to a second embodiment of the present invention is explained below with reference to FIGS. 4A, 4B, 5A, 5B, 5C, 6A, 6B, and 6C. FIG. 4A is an exploded view of an overall configuration of the heat sink 20 according to the second embodiment and FIG. 4B is a side view of the heat sink 20. FIGS. 5A and 5B are a plan view and a side view of a radiator fin 21 depicted in FIG. 4A, respectively. FIG. 5C is a partial view of the radiator fin 21 and depicts a part 50 of FIG. 5B. FIGS. 6A and 6B are a plan view and a side view of a base heat sink 25 depicted in FIG. 4A, respectively. FIG. 6C is a partial view of the base heat sink 25 and depicts a part 60 of FIG. 6B. A feature of the heat sink 20 according to the second embodiment is that the heat sink 20 has a structure that a plurality of the radiator fins 21 are connected in a multilayered state without using a pair of the fastening screws 17 as illustrated in the first embodiment.

In other words, as depicted in FIGS. 5A to 5C, a fixed base 23 in a small disk shape is fixedly provided in the substantial center on the underside of the radiator fin 21, and a mounting axis 24 including a screw part formed at its tip end is fixedly provided in the substantial center on the fixed base 23. Similarly, a screw hole 22 that the screw part of the mounting axis 24 fixedly provided on the fixed base 23 can screw in is formed in the substantial center on the upper side of the radiator fin 21.

On the other hand, as depicted in FIGS. 6A to 6C, a screw hole 26 that the screw part of the mounting axis 24 of the fixed base 23 of the radiator fin 21 can screw in is formed also in the substantial center of the base heat sink 25.

A configuration example of the heat sink 20 that uses the radiator fins 21 and the base heat sink 25 is explained below with reference to FIGS. 4A and 4B. Precisely, to begin with, a tip end of the mounting axis 24 provided on the underside of the radiator fin 21 to be positioned in the middle (the second place) is screwed to the screw hole 22 formed on the upper side of the radiator fin 21 to be positioned at the lowest (the third place). Then, a tip end of the mounting axis 24 on the underside of the radiator fin 21 to be positioned at the highest (the first place) is screwed to the screw hole 22 on the upper side of the radiator fin 21 in the middle (the second place). Accordingly, three separated pieces of the radiator fins 21 are connected to each other and integrated by fastening with the mounting axis 24 and the screw hole 22. Then, a tip end of the mounting axis 24 on the underside of the radiator fin 21 to be positioned at the lowest (the third place) is screwed to the screw hole 26 formed on the upper side of the base heat sink 25. Accordingly, the heat sink 20 that the radiator fins 21 are piled in multiple layers can be mounted on the electronic device A. Similarly to the first embodiment, the underside of the base heat sink 25 is fixed onto the upper surface of the electronic device A by using, such as an adhesive.

According to the second embodiment, a plurality of the radiator fins 21 can be connected to each other by screwing in and fastening a screw part formed at a tip end of the mounting axis 24 provided on each of the radiator fins 21 to the screw hole 22 of the radiator fin 21 to be connected, so that the heat sink 20 can be constructed; therefore a suitable heat sink can be easily constructed in accordance with an arrangement of electronic parts. Moreover, the need for the fastening screws 17 used in the first embodiment can be eliminated, consequently, the number of parts can be reduced.

[c] Third Embodiment

A configuration of a heat sink 30 according to a third embodiment of the present invention is explained below with reference to FIGS. 7A, 7B, 8A, 8B, 8C, 9A, 9B, and 9C. FIG. 7A is an exploded view of an overall configuration of the heat sink 30 according to the third embodiment and FIG. 7B is a side view of the heat sink 30. FIGS. 8A and 8B are a plan view and a side view of a radiator fin 31 depicted in FIG. 7A, respectively. FIG. 8C is a partial view of the radiator fin 31 and depicts a part 80 of FIG. 8B. FIGS. 9A and 9B are a plan view and a side view of a base heat sink 35 depicted in FIG. 7A, respectively. FIG. 9C is a partial view of the base heat sink 35 and depicts a part 90 of FIG. 9B. As depicted in FIGS. 7A and 7B, a feature of the heat sink 30 according to the third embodiment is that the heat sink 30 is constructed under a state that a plurality of the radiator fins 31 are piled in multiple layers without using the fastening screws 17, similarly to the second embodiment.

In other words, as depicted in FIGS. 8A to 8C, a fixed base 33 in a small disk shape is fixedly provided in the substantial center on the underside of the radiator fin 31, and a mounting axis 34 is fixedly provided in the substantial center on the fixed base 33. Moreover, a concave hole 32 into which a tip end of the mounting axis 34 fixedly provided on the fixed base 33 can fit is formed in the substantial center on the upper side of the radiator fin 31.

On the other hand, as depicted in FIGS. 9A to 9C, a concave hole 36 into which the tip end of the mounting axis 34 fixedly provided on the fixed base 33 of the radiator fin 31 can fit is formed also in the substantial center of a base heat sink 35. According to the third embodiment, although the mounting axis 34 and the concave hole 36 are combined at one position; the mounting axes 34 and the concave holes 36 can be combined at two positions; in such case, the radiator fins 31 can be connected to each other more strongly.

An example of a connecting method of the heat sink 30 that uses the radiator fins 31 and the base heat sink 35 is explained below with reference to FIGS. 7A and 7B. Precisely, to begin with, a tip end of the mounting axis 34 provided on the underside of the fixed base 33 of the radiator fin 31 to be positioned in the middle (the second place) is fitted into the concave hole 32 formed on the upper side of the radiator fin 31 to be positioned at the lowest (the third place).

Then, similarly, a tip end of the mounting axis 34 provided on the underside of the fixed base 33 of the radiator fin 31 to be positioned at the highest (the first place) is fitted into the concave hole 32 formed on the upper side of the radiator fin 31 in the middle (the second place). Then, under a state that the radiator fins 31 are piled in multiple layers and connected to each other, the underside of the radiator fin 31 positioned at the lowest (the third place) is mounted on the upper side of the electronic device A, and fixed by using, such as an adhesive.

As described above, according to the third embodiment, a plurality of the radiator fins 31 can be connected to each other by fitting in a tip end of the mounting axis 34 provided on each of the radiator fins 31 to the concave hole 32 of the radiator fin 31 to be connected, so that the heat sink 30 can be constructed; therefore a suitable heat sink can be easily constructed in accordance with an arrangement of electronic parts. Moreover, also in the case of the third embodiment, the need for the fastening screws 17 used in the first embodiment can be eliminated, consequently, the number of parts can be reduced.

[d] Fourth Embodiment

A configuration of a heat sink 40 according to a fourth embodiment of the present invention is explained below with reference to FIGS. 10A, 10B, 11A, 11B, 12A, and 12B. FIG. 10A is an exploded view that depicts an overall configuration of the heat sink 40 according to the fourth embodiment and FIG. 10B is a side view of the heat sink 40. FIG. 11A is a plan view of the first and the second radiator fins 41(1) depicted in FIG. 10A and FIG. 11B is a plan view of the third radiator fin 41(2) depicted in FIG. 10A. FIGS. 12A and 12B are a plan view and a side view of a radiator fin 41 depicted in FIG. 10A, respectively. A feature of the heat sink 40 according to the fourth embodiment is a configuration in no need of a base heat sink that is used in the first to third embodiments; specifically, one piece of the radiator fin 41 from among (the three pieces of) the radiator fins 41 is used as a mounting base that has a function similar to the function of a base heat sink.

In other words, as depicted in FIGS. 12A and 12B, a fixed base 43 in a small disk shape is fixedly provided in the substantial center on the underside of the radiator fin 41, and a pair of through holes 44 configured to allow two of fastening screws 48 to be inserted through, and a pair of screw holes 45 configured to allow tip ends of two of the fastening screws 48 to screw in, are formed on a diagonal line between two points, and pierced through the upper surface of the radiator fin 41 and the fixed base 43. Moreover, a fitting part 42 into which the head 18 of the fastening screw 48 can fit is formed on each upper part of the pair of the through holes 44 and the pair of the screw holes 45.

A configuration example of the heat sink 40 that uses the radiator fin 41 and the fastening screws 48 is explained below with reference to FIGS. 10A and 10B. Precisely, as depicted in FIGS. 10A and 10B, to begin with, two pieces of the radiator fins 41 are arranged so as to match pairs of the through holes 44 formed on the fixed bases 43 of the first and the second ones of the radiator fins 41 from among the three pieces of the radiator fins 41. Then, the position of the third one of the radiator fin 41 is arranged at a position that is turned by 90 degrees from the first and the second ones of the radiator fins 41. Specifically, the three pieces of the radiator fins 41 are arranged so as to match the through holes 44 of the first and the second ones of the radiator fins 41 with the screw holes 45 of the third one of the radiator fin 41. Then, two fastening screws are inserted through each of the through holes 44 of the first and the second ones of the radiator fins 41, and further screw parts formed at tip ends of the two of the fastening screws 48 are screwed into a pair of the screw holes 45 of the third one of the radiator fin 41, and fastened. Accordingly, a plurality of (the three pieces of) the radiator fins 41 in a multilayered state can be configured as the heat sink 40. Finally, the underside of the fixed base 43 of the third one of the radiator fin 41 is fixed onto the upper surface of the electronic device A by using, such as an adhesive. Accordingly, the heat sink 40 that the radiator fins 41 are piled in multiple layers can be mounted on the electronic device A.

According to the fourth embodiment, a plurality of the radiator fins 41 is connected to each other by inserting the fastening screws 48 through each of the through holes 44 of the first and the second ones of the radiator fins 41, and furthermore, screwing in and fastening the screw parts formed at the tip ends of the two of the fastening screws 48 to the pair of the screw holes 45 of the third one of the radiator fin 41; so that the need for a member that fastens a plurality of radiator fins (base heat sink) used in the first embodiment can be eliminated, consequently, the number of parts can be reduced.

Although a heat sink that is configured to separate radiator fines is explained above according to the first to the fourth embodiments, the radiator fins in an arbitrary shape can be an integral structure. In such case, a mounting work of a heat sink as radiator fins formed in a plurality of arbitrary shapes can be easily performed.

Application examples of the present invention are explained below with reference to FIGS. 13 to 16. FIG. 13 depicts an example that a heat sink 10 a according to an embodiment of the present invention is mounted on the upper surface of the electronic devices A provided on the both sides of the printed board P. According to the example in FIG. 13, the radiator fins 11 included in the heat sink 10 a are four pieces; the size of three pieces (a first piece, a second piece, and a third piece) of the radiator fins 11 among the four pieces is the same width T; and the size of the radiator fin 11 positioned at the lowest (a fourth piece) is formed as the radiator fin 11 having a small diameter (width T1).

In such case, explaining by using the heat sink 10 a positioned in the upper part of FIG. 13, a certain spatial region is formed between the underside of the radiator fin 11 that is formed in a large diameter and positioned at the third place from the top of the structure of the heat sink 10 a, and the outer circumferential side of a radiator fin 11 a that is formed in a small diameter and positioned at the lowest (the fourth place); and the spatial region is a region in which electronic parts can be arranged. Accordingly, as depicted in the figure, electronic parts, such as the damping resistance R and/or the bypass capacitor C, can be arranged in the vicinity of the electronic device A. As a result, good electrical characteristics can be achieved by the electronic parts, such as the damping resistance R and/or the bypass capacitor C. Moreover, as depicted in the figure, high-density packaging is available because there is no necessity to arrange electric parts by keep a distance from the electronic device A.

FIG. 14 depicts an example that the electronic devices A are arranged in a staggered manner on the both sides of the front and the back of the printed board P, and the heat sink 10 a is mounted on each of the electronic devices A. Also in such case, similarly to FIG. 13 described above, a spatial region is formed between the underside of the radiator fin 11 at the third place having a large diameter included in the heat sink 10 a, and the outer circumferential side of the radiator fin 11 a at the lowest having a small diameter; and the spatial region is a region in which electronic parts can be arranged. Accordingly, electronic parts, such as the damping resistance R or the bypass capacitor C, can be arranged in the vicinity of the electronic device A. As a result, good electrical characteristics can be achieved by the damping resistance R and/or the bypass capacitor C, and high-density packaging of peripheral parts and electric parts can be implemented.

FIG. 15 depicts an example that there is an insert region (a part enclosed by broken lines in FIG. 15) of a plug that connects an optical module underneath the printed board P, and the heat sink 10 a is mounted on the electronic device A. Also in such case, similarly to FIG. 13 described above, a spatial region can be formed on the underside of the radiator fin 11 having a large diameter included in the heat sink 10 a, and on the outer circumferential side of the radiator fin 11 a having a small diameter; and the spatial region is a region in which electronic parts can be arranged; accordingly, electronic parts, such as the damping resistance R or the bypass capacitor C, can be arranged in the vicinity of the electronic device A. As a result, good electrical characteristics can be achieved by the damping resistance R and/or the bypass capacitor C, and high-density packaging of peripheral parts and electric parts can be implemented.

FIG. 16 depicts an example that the heat sink explained in the first to the fourth embodiments is applied to a printed board of a stack type. Precisely, depicted is an example that the electronic device A mounted on the printed board P of the main side faces to the back side of a printed board P′ of the sub side, and a heat sink 10 b is provided on the electronic device A. Two circuit parts are mounted on the back side of the printed board P′ of the sub side.

Precisely, as depicted in FIG. 16, the heat sink 10 b is configured such that three radiator fins (first piece, second piece, and third piece) among a plurality (four pieces) of radiator fins 11 and 11 b included in the heat sink 10 b are the radiator fins 11 b having a small diameter (width T1), and one piece of the radiator fin 11 positioned at the lowest side is the radiator fin 11 having a large diameter (width T). In such case, as depicted in the figure, a spatial region without contact with the radiator fin 11 b and circuit parts can be formed below the printed board P′ by the three pieces of the radiator fins 11 b formed in a small diameter and one piece of the radiator fin 11 formed in a large diameter. Accordingly, the circuit parts provided on the back side of the printed board P′ can be arranged in the spatial region, thereby achieving high-density packaging.

Specifically, because a spatial region is formed in the heat sink 10 b by the three pieces of the radiator fins 11 b formed in a small diameter, the need for an arrangement of circuit parts with a distance in a horizontal direction not to give contact of the circuit parts to the radiator fins can be eliminated. Moreover, similarly, because circuit parts can be arranged in the spatial region, the need for arranging circuit parts by keeping a distance L (FIG. 22B) in the height direction as conventionally done is eliminated, consequently a distance (L1) between the printed board P′ of the sub side and the printed board P of the main side can be made small, thereby implementing high-density packaging of peripheral parts and electronic parts.

According to the embodiments of the present invention, a heat sink that has heat dissipation characteristics (cooling function) can be easily constructed by combining a plurality of radiator fins formed in an arbitrary shape; and high-density packaging of peripheral electronic parts can be implemented by using radiator fins appropriate to an arrangement of electric parts; so that a heat sink that is planned to achieve good electrical characteristics and designed at low cost without spending time and effort for a customized design can be implemented.

Furthermore, according to the embodiments of the present invention, one of the radiator fins can be used as a radiator fin for connection, thereby reducing the number of parts.

Moreover, according to the embodiments of the present invention, radiator fins can be configured as a heat sink by connecting the radiator fins in a multilayered state with a screw member.

Furthermore, according to the embodiments of the present invention, mounting screw that connects radiator fins to each other is not needed, so that the number of parts can be reduced, and a mounting work of a heat sink including a plurality of radiator fins can be easily performed.

Moreover, according to the embodiments of the present invention, a mounting work of a heat sink that is a plurality of radiator fins formed in an arbitrary shape can be easily performed.

Furthermore, according to the embodiments of the present invention, a heat sink favorable for general purpose can be constructed in accordance with an arrangement of an electronic device and electronic parts.

All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention. 

1. A heat sink comprising: radiator fins for dissipating heat of an electronic device provided on a printed board, wherein the heat sink is constructed by piling radiator fins formed in an arbitrary shape into multiple layers in a height direction and connecting the radiator fins.
 2. The heat sink according to claim 1, further comprising a base heat sink configured to be fixed on an electronic device provided on the printed board; and a fastening unit that fastens the radiator fins into a multilayered state in the height direction.
 3. The heat sink according to claim 1, further comprising a fastening unit that fastens the radiator fins to each other, wherein the radiator fins are formed with a through hole that the fastening member pierces, and a screw hole with which a screw part formed at a tip end of the fastening member is to be screwed, and the fastening unit pierces through holes of the radiator fins, and fastens the radiator fins into a multilayered state in the height direction by screwing into a screw hole of the radiator fins positioned underneath the radiator fins.
 4. The heat sink according to claim 2, wherein the fastening unit is a screw member that pierces a through hole formed at a certain position on the radiator fins under a state that the radiator fins are piled in multiple layers in the height direction, and is fastened to a screw hole formed at a certain position on the base heat sink.
 5. The heat sink according to claim 2, wherein the fastening unit includes a screw fastening member that can screw into a screw hole formed on an upper surface of the radiator fins and the screw hole provided underneath the radiator fins, and the screw fastening member is configured to be screwed to a screw hole formed on an upper surface of the base heat sink.
 6. The heat sink according to claim 2, wherein the fastening unit includes a concave hole formed on an upper surface of the radiator fins and a convex member that can fit in the concave hole, the concave hole being provided underneath the radiator fins, and the convex member being configured to fit in a concave hole formed on an upper surface of the base heat sink.
 7. The heat sink according to claim 1, wherein the radiator fins are a structure in which a plurality of fins formed in an arbitrary shape is integrated.
 8. The heat sink according to claim 1, wherein the radiator fins are each formed in respective shapes in different sizes in accordance with an arrangement of electronic parts provided on the printed board.
 9. The heat sink according to claim 1, wherein the radiator fins are each formed in respective shapes in different sizes in accordance with a height of electronic parts provided on the printed board. 